There are a variety of dampers in automotive suspensions, including a mono-tube type strut, a twin-tube type strut, and a triple-tube type strut. Within each variation, there are variations with valve arrangement and fluid management. The triple-tube type strut construction includes tube and valve arrangement that allows for fluid flow within the strut that is generally in a single direction for both the compression and rebound direction of the suspension strut, whereas both mono-tube and twin-tube type struts require fluid to flow in different directions for the compression and rebound directions. This single-direction property of the triple-tube type strut allows for damping control of the fluid flow within the triple-tube type strut to be localized to one general area within the strut for both compression and rebound directions. As a result, conventional semi-active or continuously variable damping control systems typically utilize the triple-tube type strut and a single active solenoid valve to control damping force for both the compression and rebound directions of the strut.
Conventional triple-tube type strut dampers include many internal parts that function to tune the dampening properties of the strut and are, for this reason, quite complex. Additionally, the damping mechanisms that are utilized in such triple-tube type struts may leak, decreasing the efficiency of the damper, or may be relatively expensive. As shown in FIG. 1 (prior art), the active valve 10 in typical triple-tube type strut dampers is often mounted perpendicular to the long axis of the damper tube 12 and substantially adjacent to the base valve 14 that allows replenishment flow to the inner cavity 16 during the rebound stroke of the strut. This may allow such triple-tube type strut dampers to increase the range of travel of the suspension strut given a total strut height. However, this arrangement requires a fastening mechanism that does not benefit from the compressive forces from tube assembly and/or the vehicle. In semi-active or continuously variable damping control systems that utilize compressible fluids where the pressure within the suspension strut may increase to substantially high levels, the fastening mechanism used to mount the active valve perpendicularly to the axis of the damper tube may become substantially costly to withstand such high pressures. Because of complexity of typical triple-tube type strut dampers, cost is relatively high and adoption of such semi-active or continuously variable damping control systems in the field is substantially impaired.
Thus, there is a need in the vehicle suspension field to create an improved suspension strut. This invention provides such strut.